Method for producing a component and/or a coating comprised of a vibration-damping alloy or intermetallic compound, and component produced using this method

ABSTRACT

A method for producing a component and/or a coating from a vibration-damping alloy or intermetallic compound includes producing the component and/or the coating via thermal spraying.

[0001] This application claims the priority of German application 102 08868.3, filed Mar. 1, 2002, the disclosure of which is expresslyincorporated by reference herein.

BACKGROUND AND SUMMARY OF THE INVENTION

[0002] The present invention relates to a method for producing acomponent and/or a coating comprised of a vibration-damping alloy orintermetallic compound. The invention also relates to a componentproduced using such a method.

[0003] Shape-memory alloys, as an example, are suitable for use invibration damping, provided their structure is correspondingly designed.

[0004] Shape-memory alloys have long been known in the art. For example,German patent document DE 40 06 076 C1 describes a NiTi shape-memoryalloy which, with a nearly stoichiometric composition, is characterizedby an especially high degree of reversible deformation in one-way andtwo-way effects, high tensile strength and ductility, and a very highresistance to corrosion. Furthermore, this shape-memory alloy exhibitsan outstanding degree of shape-memory effect stability with respect tothermal cycles. In addition, this alloy can be heated relatively farbeyond the A₁ temperature (temperature of the completion of austeniteformation) without developing damaging irreversible structural changeswhich reduce the degree of shape-memory effect or undesirably shift theconversion temperature.

[0005] An iron-nickel-cobalt-titanium shape-memory alloy and a methodfor producing the alloy are known from German document DE 41 20 346 A1.According to this publication, the shape-memory alloy is produced via acasting method, after which it is deformed at temperatures of between1,050° C. and 1,052° C., and then quenched; it is then subjected to asolution treatment over a period of 10 to 30 hours at temperatures ofbetween 1,150° C. and 1,250° C. in an inert gas atmosphere, after whichit is again quenched. To generate the shape-memory effect, theshape-memory alloy is exposed to temperatures of between 500° C. and650° C. for a period of between 10 minutes and 150 hours, after which itis quenched for a third time and then subjected to training deformationinvolving one to fifty repetitions.

[0006] A method for producing Cu/Zn/Al-type shape-memory alloys via apowder-metallurgical process is known from WO 81/02587. In this method,the finished powder is encapsulated, cold-compressed, heat-compressed,and extruded. In practice, however, this method does not fulfill allnecessary requirements, and the formed components often are inadequatein terms of their mechanical properties.

[0007] Another method known from this publication involves againproducing the shape-memory alloy, via a powder-metallurgical process, asa fine-grained memory alloy of the Cu/Zn/Al type with a β-hightemperature phase, and with dispersoids in the form of Y₂O₃ and/or TiO₂particles embedded in the matrix that serve to inhibit grain growth. Theproduction process is accomplished with the help of mechanical alloying.

[0008] Further known shape-memory alloys are produced via apower-metallurgical process with a subsequent hot-isostatic pressuretreatment, extrusion molding treatment, or forging treatment.

[0009] One object of this invention is to further develop a method forproducing a component and/or a coating from a vibration-damping alloy orintermetallic compound such that the properties are improved, the rangeof application is expanded, and the production process is simplified.

[0010] This object is attained with respect to the method by producingthe at least one of the compound and the coating via thermal spraying.

[0011] Further advantageous features of the invention are reflected independent claims.

[0012] Pursuant to the invention, a component and/or a coating are/isproduced via a thermal spraying process. In this process, the metalliccoating material is deposited on the surface of a carrier material orcomponent in the form of heated and accelerated spray particles. Precisetemperature control combined with a high particle speed results information of vibration-damping properties. In the thermal sprayingprocess, for example, a solid object is coated with a heated andaccelerated metallic material, which e.g. is fed into a thermal spraygun in the form of powder or wire. The surfaces of the solid object arenot fused during the spray process. During spraying attemperatures >850° C., interdiffusion takes place between the componentand the applied layer. Thus, at low coating temperatures, adhesion ispreferably the result of physical interaction. A metallurgical linkagethen occurs in conjunction with the coating process via diffusionannealing at temperatures >800° C. Precise temperature control duringthe coating process is essential for formation of a well-definedstructure. This spraying process may also be used to spray materialsthat are not miscible with the base metal and/or that form brittle,intermetallic compounds.

[0013] According to one embodiment, plasma spraying within a vacuum isused as the spraying process. With plasma spraying in a vacuum, gasplasma is used as the heat source for heating and accelerating thematerial to be used. Spraying within a vacuum prevents the formation ofoxide streaks as a result of the oxidation of the sprayed materialduring the coating process, and positively affects the structuralformation.

[0014] Preferably, however, an RSPD (rapid solidification processingdeposition, in which alloys are deposited on a carrier via atomizationfrom the molten bath, with extremely rapid hardening) process can beused as the spray process for producing a coating or a component.

[0015] Alternatively, a high-speed powder or plasma spray process may beused as the spraying process. With high-speed powder spraying,combustion of a fuel gas-oxygen mixture takes place in a combustionchamber. The pressure that builds up within the chamber results in highparticle speeds in a connected expansion nozzle. Both methods result inimproved adhesion and coating density.

[0016] In accordance with another embodiment, a cold-kinetic compactionprocess can be used as the spraying method.

[0017] In order to ensure a high resistance to corrosion, anickel-titanium alloy—as described in German publication DE 197 41019—is used. This alloy is formed into a component in accordance withthe method described above, or is applied to a component as a coating.The disclosure of German publication DE 197 41 019 also applies inconnection with this application.

[0018] The temperature during the spraying process preferably is between1000° C. and 1,000° C.

[0019] According to one embodiment of the invention, thevibration-damping alloy is applied to a component as a coating. Theadvantage of this is that the material can be applied via the methodindicated in the form of a coating of any desired thickness. With theprocess specified in the invention, components and semi-finishedproducts can be produced, and components and machinery elements can alsobe coated in a simple manner. The vibration damping achieved via theapplication of a coating can be established locally at specific pointson a component. In this way, high stability and rigidity of thecomponent can be combined with good damping properties. For example,components, especially engine components and machine tool components,which are supplied with a vibration-damping coating in accordance withthe invention, exhibit significantly improved vibration behavior, andthus improved operating results.

[0020] In contrast to current damping elements made of rubber orplastics, higher thermal stress on the coated components and machineryelements is possible. In addition, the coating and the component exhibithigh bond strength.

[0021] Basically, coatings of any thickness and any geometry can beproduced. Preferably, the vibration-damping alloy is applied to thecomponent as a coating measuring 0.1 to 25 mm in thickness.

[0022] In order to increase the bond strength between the coating andthe component, the surface of the component to be coated is preparedprior to coating, for example via an abrading process, such as anirradiation process, e.g. laser or arc exposure, or plasma etching.

[0023] Preferably, following the application of the coating, adiffusion-heat process is conducted in order to increase the adhesion ofthe coating to the component.

[0024] After the coating process, the layer applied to the componentpossesses vibration-damping properties.

[0025] To produce components, especially machinery elements, experimentswere conducted using titanium and steel sheets, which were coated with anickel-titanium shape-memory alloy. This coating was applied, via plasmaspraying in a vacuum, to a thickness of up to 0.5 mm. To produce aconnection to the material of the component that is metallurgically freefrom defects, the test samples were heated prior to coating and cleanedusing an arc.

[0026] A metallographic evaluation shows a dense coating with a verysecure connection to the carrier material that is metallurgically freefrom defects, with a porosity of <1%.

[0027] The damping properties were verified in the first stage using anacoustic sampling and attenuation measurements.

[0028] With the method specified, both semi-finished products andcomponents can be produced from, and thus coated with, avibration-damping alloy, e.g., a shape-memory alloy, or avibration-damping intermetallic compound. A further application of theprocess specified in the invention involves components from the field ofengines, such as housings, disks, and blades that are vibration-dampedwith a coating and thus are placed under reduced stress, resulting in alonger lifespan.

[0029] Application of the coating via the process specified to machineryelements for the purpose of passive vibration damping is especiallyadvantageous for cutting machine tools, as it allows significantlyimproved processing results in the surface quality achieved, along withhigher processing speeds with materials that are difficult to machine.

[0030] Further, any case in which the coatings are applied to machineryelements for the purpose of vibration damping, in accordance with theabove-described process, is advantageous when a high degree of bondstrength and high thermal and corrosion resistance are required.

[0031] The invention will be described below in greater detail withreference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 is a perspective view of a fixed blade segment of a gasturbine, and

[0033]FIG. 2 shows a tool-receiving socket with a tool.

DETAILED DESCRIPTION OF THE DRAWINGS

[0034]FIG. 1 shows a fixed blade segment 1 of a gas turbine that hasbeen coated in accordance with the invention. The four fixed blades ofthe segment 1 that are bombarded by the operating gas are provided atleast over a majority of their surfaces with a vibration-damping coating2 comprised of a suitable alloy or intermetallic compound.

[0035]FIG. 2 shows a component in the form of a tool-receiving socket 3for a milling cutter 4 or some comparable tool, wherein thetool-receiving socket 3 as a whole is made of a vibration-damping alloyor a vibration-damping, intermetallic compound.

[0036] The foregoing disclosure has been set forth merely to illustratethe invention and is not intended to be limiting. Since modifications ofthe disclosed embodiments incorporating the spirit and substance of theinvention may occur to persons skilled in the art, the invention shouldbe construed to include everything within the scope of the appendedclaims and equivalents thereof.

We Claim:
 1. A method for producing at least one of a compound and acoating comprised of a vibration-damping alloy or intermetalliccompound, comprising producing the at least one of the compound and thecoating via thermal spraying.
 2. The method according to claim 1,wherein the thermal spraying is plasma spraying in a vacuum.
 3. Themethod according to claim 1, wherein the thermal spraying is performedby rapid solidification processing deposition.
 4. The method accordingto claim 1, wherein the thermal spraying is high-speed powder or plasmaspraying.
 5. The method according to claim 1, wherein the thermalspraying is a cold-kinetic compaction process.
 6. The method accordingto claim 1, wherein the vibration-damping alloy is a nickel-titaniumalloy.
 7. The method according to claim 1, wherein a temperature duringthe thermal spraying is between 100° C. and 1,000° C.
 8. The methodaccording to claim 1, wherein the vibration-damping alloy is applied toa component as a coating having a thickness of 0.1 to 25 mm.
 9. Themethod according to claim 1, wherein a surface of a component to becoated is prepared prior to application of the coating in order toincrease bond strength between the coating and the component.
 10. Themethod according to claim 9, wherein the surface is prepared via anabrading process.
 11. The method according to claim 1, and furthercomprising subjecting the coating to thermal treatment followingapplication of the coating to a component.
 12. The method according toclaim 10, wherein the abrading process is an irradiation process. 13.The method according to claim 12, wherein the irradiation process isperformed by laser or arc exposure.
 14. The method according to claim 9,wherein the surface is prepared via plasma etching.
 15. A componentproduced in accordance with the method of any of claims 1-14.